Screening colonoscopy and colorectal cancer: a single center long term study

In Germany, colonoscopy has been introduced as a screening instrument more than 10 years ago. Immediate outcome (complications and adenoma detection) is well documented in a nation wide register, but there is only limited information on the decisive end points: long term incidence and mortality of colorectal carcinoma.We therefore tried to contact all those 495 subjects (296 women and 199 men, mean age 63.9 years) that had been screened between 2003 and 2005  at our institution. We were able to trace 472 persons (96 %), 5.1 to 7.8 years after colonoscopy; a total of 2730 person years were analysed. Data were collected by direct telephone calls and follow up colonoscopy reports were retrieved.Four malignant lesions were identified at screening. Another two colorectal carcinomas were diagnosed three and seven years after adenoma-negative colonoscopies: an advanced rectum carcinoma (index endoscopy described inadequate bowel preparation) and a coecum tumor. The patient with the rectum tumor subsequently died from the disease. The other five patients with colorectal carcinoma are disease-free. - Compliance with surveillance was limited, only 38 of 60 patients with advanced benign lesions and 49 out of 82 patients with a small tubular adenoma had a repeat colonoscopy, and this was performed a mean of 1.1 years later than advised. About half of the screened subjects were completely unaware of a recommended control interval or grossly wrong about it.We conclude that colorectal carcinomas can occur despite screening colonoscopy, but this seems to be a rare event. Subjects screened are insufficiently informed as to recommendations on post-polypectomy surveillance. This is particularly worrying in the high risk group with benign, but advanced adenomas.